In recent years, services provided over a network have grown to include provision of copyrighted works such as music and videos, viewing of classified material retained by corporations, online banking, etc. The value of the information contained in these services has also become considerably high. To accommodate this wide range of services, a plurality of software modules are installed on personal computers, portable terminals, cellular telephones, terminals of digital home appliances, etc. Such software modules include, for example, BIOS (Basic Input/Output System), OS (Operating System), communications modules that make it possible to communicate with the outside via communications protocols such as TCP/IP (Transmission Control Protocol/Internet Protocol), etc., as well as applications and the like.
Legitimate software modules need to be booted in a predetermined order, and a mechanism for preventing improper activities such as manipulating the software modules is installed in the terminals. One example of such a mechanism is having a provider issue a certificate for each software module. When each software module is booted, the integrity of the software module is verified using the certificate. This mechanism is also effective when updating an entire software module: as the provider of the software module provides a certificate for the software module along with the software module, it is possible to verify the integrity of the new software module.
Similar technology to this mechanism for preventing improper action using a certificate is disclosed, for example, in Patent Document 1.
Furthermore, the Trusted Computing Group (TCG) has been established for the purpose of developing and spreading a secure computer platform. The TCG uses a security core module called a Trusted Platform Module (TPM) to create a safe terminal environment (Cf. Non-Patent Documents 1-5).    Patent Document 1: US2005/0021968    Non-Patent Document 1: TPM Main, Part 1 Design Principles, Specification Version 1.2 Level 2, Revision 103 (9 Jul. 2007).    Non-Patent Document 2: TPM Main, Part 2 Structures, Specification Version 1.2 Level 2, Revision 103 (9 Jul. 2007).    Non-Patent Document 3: TPM Main, Part 3 Commands, Specification Version 1.2 Level 2, Revision 103 (9 Jul. 2007).    Non-Patent Document 4: TCG Mobile Trusted Module Specification Version 1.0, Revision 1 (12 Jun. 2007).    Non-Patent Document 5: TCG Mobile Reference Architecture Specification Version 1.0, Revision 1 (12 Jun. 2007).